This paper was published in Bioresource Technology 2010 Mar;101(5):1471-6
Study title and authors;
Recovery of phytosterols from waste residue of soybean oil deodorizer distillate.
Yang H, Yan F, Wu D, Huo M, Li J, Cao Y, Jiang Y.
Key Laboratory of Hollow Fiber Membrane Materials and Processes of the Ministry of Education, School of Material Science and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160, PR China.
This study describes a crystallization process used to recover soy phytosterols from the waste residue of soybean oil deodorizer distillate (WRSODD).
Where does the waste residue of soybean oil deodorizer distillate originate from?
Intially oil is extracted from soybeans using a solvent called hexane. (Hexane is a chemical byproduct of gasoline refining and has been identified by the FDA as a potent neurotoxin and a carcinogen.). The oil is then refined, sometimes hydrogenated and is sold as vegetable oil, or ends up in a wide variety of processed foods. The refining process includes (i) degumming, (ii) neutralization, (iii) bleaching and (iv) deodorization.
(i) Degumming:
Crude soy oil contains gums such as phospholipids and other compounds that require removal before the deodorization stage, as they cause the oil to darken when heated. Extracted phospholipids are sold as lecithin. Solvents such as phosphoric acid and acetic anhydride are used in the degumming process. (Phosphoric acid is a corrosive acid and can form toxic fumes whact with other compounds. Acetic anhydride causes skin and eye burns and irritation of the respiratory tract. Nausea and vomiting may develop after exposure).
The degumming process itself also has undesirable effects such as contaminating oil with inorganic phosphates, degrading recovered phospholipids, and corroding stainless steel equipment.
(ii) Neutralization:
The degummed oil undergoes neutralization with a caustic alkaline solution followed by acid treatment. There are concerns that neutralization impairs the nutritional quality of oils, particularly the vitamin, mineral and protein content, and also adds potential carcinogenic compounds such as nitrosamines.
(iii) Bleaching:
The neutralized oil is then bleached which has the unfortunate effects of removing nutrients such as carotenoids and causing the fatty acids to go rancid.
(iv) Deodorization:
After the bleaching process, the oil is deodorized which eliminates beneficial components such as tocopherols from the oil.
Soybean oil deodorizer distillate is a waste product of the above soybean oil refining process. The soy
phytosterols are then removed from the soybean oil deodorizer distillate by various solvents.
This study describes various solvents used in the phytosterol removal process.
(a) Ethanol:
Ethanol is another name for alcohol. E.g most wines contain less than about 13% ethanol. A denaturant is added to industrial ethanol, which is a substance which makes the ethanol both unpalatable and poisonous.
(b) n-propanol:
Can injure eye tissue, cause skin irritation and may aggravate asthma-like conditions. In laboratory studies n-propanol has been shown to lower male fertility, harm the fetus and cause an increase in cancer.
(c) Hexane:
Hexane exposure has been linked with skin irritation, dry skin, pain in skin, irritation, pain and redness in eyes, abdominal pain, nausea, vomiting, drowsiness, dizziness, dullness, weakness, headache, upper airway irritation, breathing difficulty, muscle cramps, tinnitus, muscle wasting and symptoms of peripheral neuropathy in cases of chronic exposure.
Hexane can also cause cancer, and other serious health illnesses including reproductive and birth defects. Hexane has been linked to explosions in food processing units. It is a potent neurotoxin causing dangerous health effects in workers of food processing units.
(d) Cyclohexane:
Causes skin irritation, drowsiness, dizziness and may be fatal if swallowed and enters the airways.
(e) Petroleum ether (benzine):
Petroleum ether is a flammable liquid obtained in distilling petroleum and is used in cleaning and dyeing and as a motor fuel.
(f) Acetone:
May cause irritation to the eyes throat and respiratory system, mood swings, and nausea. In laboratory studies acetone has been shown to cause anemia and an increase in malformed sperm.
(g) Butanone:
Butanone is an irritant, causing irritation to the eyes and nose. Butanone has induced birth defects, liver tumours and mammary gland tumours in laboratory studies.
(h) Cyclohexanone:
Exposure to cyclohexanone can result in irritation to the eyes, nose, throat and skin. It may cause dizziness and unconsciousness. Studies have shown that cyclohexanone may cause cataracts.
(i) Benzene:
Benzene increases the risk of cancer, bone marrow failure and anemia.
(j) Toluene:
Toluene may cause liver, kidney neurological damage. It has been linked with irritation to the nose, throat and respiratory tract. Exposure to toluene may cause hallucinations, dizziness, drowsiness, slurred speech, tremors, respiratory depression, arrhythmias and convulsions. Coma and death can occur following substantial exposures.
After the soy phytosterols have been extracted by the above processes they are added to processed foods such as margarines, mayonnaises, vegetable oils, salad dressings, soy milk, orange juice, snack bars, low-fat milk and low-fat and non-fat beverages.
Is it healthy to eat these products that are manufactured in such an industrial manner?
